Digital Controller for Dc-Dc Switching Converters for Operation at Ultra-High Constant Switching Frequencies

a digital controller and converter technology, applied in the direction of dc-dc conversion, power conversion systems, instruments, etc., can solve the problems of long and tedious design process, inflexible and unsuitable for the integration with fast changing digital hardware, and low power consumption of analog controllers, so as to achieve power efficient operation

US20080303501A1Active Publication Date: 2008-12-11NXP BV
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2008-12-11

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Abstract

A digital controller for low-power DC-DC switch mode power supplies (SMPS) suitable for on-chip implementation and use in portable battery-powered systems is provided. The digital controller allows operation at ultra high constant switching frequencies and can be implemented with a simple low-power digital hardware. The digital controller includes a digital pulse width modulator (DPWM), based on a multibit 2nd orders sigma-delta (Σ-Δ) principle, and a dual-sampling mode PID compensator. The output voltage is either sampled at a frequency lower than the switching frequency (undersampled) or sampled at the switching rate. In steady-state, undersampling results in reduced power consumption, while during transients, sampling at the switching rate provides fast transient response. Another aspect of the present invention is a dual sampling / clocking scheme, which is relied on by the DPWM described. A method is also provided for controlling low power DC-DC switch mode power supplies operating at high constant switching frequencies.
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Description

FIELD OF THE INVENTION

[0001] This invention relates to a digital device and a method of controlling supply voltage in low-power portable devices.BACKGROUND OF THE INVENTION

[0002] Analog controlled switch-mode power supplies (SMPS) are used in low power devices such as cell phones, portable data assistants, and MP3 players, to transfer variable supply (i.e. battery) voltage to a constant output value. The regulation is performed through the interaction of an analog controller and direct-current to direct-current (DC-DC) switching power converter. The task of the controller is to monitor the output voltage and provide appropriate low-power pulse-width modulated control signals for the switching converter, which efficiently processes power. To allow small weight and size of the overall system, it is usually desirable that the controller produces signals at a high constant frequency (switching frequency fsw) that does not interfere with the proper operation of the supplied device. In the ...

Examples

experimental verification (

All-Digital FPGA Implementation)

[0067]The results of the verification demonstrated that the architecture of the present invention results in a significant increase of the switching frequencies at which digital controllers can be used. It is reasonable to assume that by transferring this design on an integrated circuit that is faster than the FPGA structure used, pulse width modulated signals at even higher frequencies (in the range of 100 MHz and about 120 MHz with optimization) could be achieved. This is based on implementation of the architecture to an integrated circuit in a manner that is known to those skilled in the art. Simulation results of such on-chip implementation are shown in FIG. 11, they verify operation at frequency of 115 MHz.

Closed Loop Operation

[0068]To further verify the operation of the controller, an experimental system based on block diagrams shown in FIG. 1 was constructed. To limit the switching losses of the buck converter switching frequency was decreased ...